There use makes our code safer so we should mention them. Signed-off-by: Alex Bennée <alex.ben...@linaro.org> --- docs/devel/style.rst | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+)
diff --git a/docs/devel/style.rst b/docs/devel/style.rst index 0bd01f3fca..b50a981a86 100644 --- a/docs/devel/style.rst +++ b/docs/devel/style.rst @@ -657,6 +657,42 @@ that declaration and the new code. See :ref:`qom` for more details. +QEMU GUARD macros +================= + +QEMU provides a number of ``_GUARD`` macros intended to make the +handling of multiple exit paths easier. For example using +``QEMU_LOCK_GUARD`` to take a lock will ensure the lock is released on +exit from the function. + +.. code-block:: c + + static int my_critical_function(SomeState *s, void *data) + { + QEMU_LOCK_GUARD(&s->lock); + do_thing1(data); + if (check_state2(data)) { + return -1; + } + do_thing3(data); + return 0; + } + +will ensure s->lock is released however the function is exited. There +are often ``WITH_`` forms of macros which more easily wrap around a +block inside a function. + +.. code-block:: c + + WITH_RCU_READ_LOCK_GUARD() { + QTAILQ_FOREACH_RCU(kid, &bus->children, sibling) { + err = do_the_thing(kid->child); + if (err < 0) { + return err; + } + } + } + Error handling and reporting ============================ -- 2.39.2